Add PHPUnit tests for script module collision behavior

[retrofox]

What?

Adds PHPUnit tests to premium-analytics that document and verify the behavior of script module collisions when multiple plugins register the same packageSources entry (e.g., @automattic/number-formatters).

Addresses WOOA7S-1346.

Follows up on the concern raised by @anomiex in PR #48089.

Why?

The generated modules.php from wp-build uses a deregister-before-register pattern to override Core defaults. When two plugins ship the same packageSources entry, this creates a last-plugin-wins collision. These tests verify the exact behavior and document the trade-offs.

How?

• Added automattic/jetpack-test-environment to premium-analytics dev dependencies for WordPress function access in tests
• Created Script_Module_Collision_Test.php with 7 tests covering:
  • Last-wins: with deregister-then-register, the last plugin to load wins
  • Older version risk: an older version overwrites a newer one if its plugin loads last
  • First-wins default: without deregister, WordPress native wp_register_script_module() is first-wins
  • Consumer dependency survival: route dependencies survive re-registration of the shared module
  • Multiple consumers: consumers from different plugins all resolve to the winning version
  • Dequeue side-effect: wp_deregister_script_module() also dequeues the module
  • Dynamic imports: dynamic import dependency types are preserved after re-registration

Findings

1. Within the Jetpack monorepo, collision risk is low because all plugins share the same pnpm-lock.yaml
2. The real risk is cross-release version skew (plugin A on release N, plugin B on release N-1)
3. This is the same trade-off that externalNamespaces already makes with @wordpress/* packages

Testing

cd projects/packages/premium-analytics
composer update
composer phpunit

All 8 tests pass (1 existing + 7 new, 19 assertions).

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[jp-launch-control]

Code Coverage Summary

Cannot generate coverage summary while tests are failing. 🤐

Please fix the tests, or re-run the Code coverage job if it was something being flaky.

Full summary · PHP report

[Copilot]

Pull request overview

Adds PHPUnit coverage to the premium-analytics package to document and lock in expected WordPress script module behavior when multiple plugins register the same packageSources module ID, particularly around the wp-build “deregister then register” override pattern.

Changes:

• Initialize the shared Jetpack WorDBless-based WordPress test environment in the PHPUnit bootstrap.
• Add a new PHPUnit test class covering multiple collision scenarios (last-wins override, first-wins default behavior, dependency survival, dequeue side-effects, dynamic imports).
• Add automattic/jetpack-test-environment as a require-dev dependency for the package.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated no comments.

File	Description
projects/packages/premium-analytics/tests/php/bootstrap.php	Initializes the shared WP test environment so WP script-module APIs/classes are available to tests.
projects/packages/premium-analytics/tests/php/Script_Module_Collision_Test.php	Adds targeted tests that simulate modules.php override behavior and assert the resulting registry/queue outcomes.
projects/packages/premium-analytics/composer.json	Adds the dev dependency needed to provide the WP test environment for this package’s PHPUnit suite.